Pneumatic PID Controller setup

Pnumatic Indicator Controller are most used in industry, the calibration of the controller is not useful if didn’t implement the alignment for the flapper and nozzle to assure controller functioning and better performance in process control.


What's to align? There could some parallax in the photos, but from the photos it appears that the instrument is within 0.5% from zero to span.

The manufacturer should have a calibration/alignment procedure.
Glad you clarified that you had a question.
So it looks like you have a Yokogawa M43 controller, probably a MC43-A5C-N*A from the looks of it. The M43 is exactly the same as a Foxboro 43AP controller, except the case is different. This brings back some memories.

Alignment refers to the things you do to get a well performing controller.
1) the set up of the process pointer linkage to give accurate reading. sometimes referred to as the process measurement (PV) calibration
2) setting the relationship of pressures in the bellows so they are in balance at the point where the PV is equal the set value.
here you are setting the force balance arrangement to a central point bias so it so free to move with equal measure in either direction in response to PV changes away from SV.
3) flapper nozzle alignment an adjustment made to set the relationship of the two to be as central & perpendicular as possible.

So if you really want to know how these controllers work try this article Pneumatic PID Controller (
First do the process measurement pointer alignment by following the steps here 43AP process alignment
Then do the control unit alignment in the manual attached. it is the Foxboro version and easier to read than the Yokogawa version.
Good Luck